SI9400362A - Procedure for the preparation of the carriers that are impregnated or coated with microcapsulated aromatic substances - Google Patents

Abstract

The invention refers to the process of preparation of carriers, impregnated or coated with microencapsulated scents, comprising the preparation of microcapsule emulsion, preparation of coating and coating or impregnation of carrier. After the preparation of emulsion it also includes emulsifying of core material into a solution of wall material base containing modifier. Such processes also comprise initiation of wall formation by raise of temperature and/or change of pH value and in addition to that also finishing or interrupting the reaction in microencapsulation by changing the pH value by which polymerization stops. According to the invention during the preparation of microcapsule emulsion in the stage of preparation of core material water for the extraction of water soluble components is emulsified into solution of essential oils and after the extraction separated from oil for which the presumed essential oils or presumed scents, especially natural essential oil, synthetic scents or their mixture, either pure or diluted with adequate solvents such as phalates, myristinats, adipates, higher non-aromatic hydrocarbons are microencapsulated and where water-soluble components are extracted from the solution of essential oils in solvents by means of water and in addition to that, during the initiation of wall, temperature is gradually increased from the value which corresponds to approximately 50 % value of temperature volatility of each essential oil or a scent to the temperature of which value is approximately 90 % value of temperature volatility of each essential oil or scent. Microencapsulated scent, binders, organic and/or inorganic pigments and fillers, anti-foaming agents for viscosity regulation are added for the preparation of coating or impregnating mixture, depending on the carrier. When coating or impregnating the carrier the coating in a form of suspension is applied by means of scraper, air knife, cylinders; when impregnating the carrier, which is a woven or non-woven material, paper, cardboard or foil of artificial material, it is transferred through the saturation basin containing impregnating mixture.

Description

The process of preparing carriers impregnated or coated with microencapsulated fragrances

The invention relates to a process for the preparation of carriers impregnated or coated with microencapsulated fragrances. According to the international patent classification, the present invention can be classified in the field of processing, in particular chemical processes (B 01 J 3/02), but also in the field of textiles (D 06 M 15/04) or paper (D 21 H 27/36) .

The invention is based on the problem, to design a method of preparing carriers, impregnated or coated with microencapsulated fragrances, by which it will be possible to obtain carriers, both impregnated and solely coated with microencapsulated fragrances, which will prevent evaporation of the fragrance and eliminate the environmental impact on the fragrance or . sensitive components thereof, thus eliminating the need for the use of environmentally friendly, impermeable packaging in such carriers, while at the same time allowing the desired and long-lasting effect of fragrances instead of the involuntary permanent and therefore short-term effect of fragrances, thereby extending the usefulness of the process of the obtained carriers .

Carriers impregnated with free fragrances (for example, essential oils) are widely used. They are known e.g. refreshing wipes, deodorant or. footwear disinfectants, deodorant towels, promotional paper slips or propagation of fragrances and similar articles, which are normally manufactured by the process of impregnating or impregnating the article with fragrances on a suitable carrier. Because the fragrances are volatile, it is necessary to pack the resulting products in special, impermeable packaging, which is environmentally friendly. Despite packaging the products in impermeable packaging, problems occur after they have been opened. While the problems are not so pronounced in products intended for immediate use, especially for single use, they are more pressing for products intended for more durable use, e.g. in the case of deodorant footwear inserts which, due to the relatively rapid evaporation of fragrances, reduce the useful life of the product very quickly. Furthermore, in the case of products obtained by the aforementioned fragrance impregnation process, in addition to the aforementioned problems of packaging and the rapid deterioration of the usefulness of the product, there are also a number of completely practical problems which are manifested e.g. in the humidity of the carrier or. the product to be felt, in the uncontrolled release of the active substance (fragrance), as well as in the exposure of fragrances to the defective or adverse effects of the environment, in particular light, temperature and air.

In the past, the problems described above have been addressed in various ways. It is known e.g. the process by which the fragrance binds to the proper adsorbents, which results in a slower release of the fragrance, but it remains unprotected against environmental influences.

Furthermore, microencapsulation processes are known to achieve a slower release of a fragrance or a first one. fragrant compositions, on the other hand, also protect them from the harmful effects of the environment.

The microencapsulation process generally makes it possible to dress emulsified particles (eg solvents or a dye funnel) in various ways, thereby preparing microcapsules with different properties and for different uses. The microcapsules thus obtained are useful in various fields, e.g. (US 2,730,456; US 4,00,103; US 474,379; EP 107,957) in the manufacture of seedless copying papers, further for the preparation in agriculture of useful controlled-release microencapsulated pesticides (GB 1,581,255; EP 17,409; YU 3109; EP 51,161), for the separation of reactants (DE 2.247.468; US 4,536.524) in two-component adhesives, in mariculture (GB 2.040.863) for the preparation of larval food, as well as in medicine for masking the taste of certain drugs and / or the controlled release of them ( US 3,860,733).

Microencapsulation is generally feasible either by mechanical or chemical processes. The latter are more suitable because it is possible to change the properties of the envelope. The chemical processes of microencapsulation can be classified into three groups, namely coacervation, interfacial polycondensation, or. polymerization and polymerization or. in situ polycondensation.

In co-conservation processes (e.g., US 2,800,457; US 2,730,456; GB 2,099,847; EP 58,430; GB 2,122,630; DE 3,424,115; DE 2,100,700 and FR 2,570,604), wall materials were most commonly used gelatin in combination with Arabic gum or other anionic polymer, e.g. carboxymethylcellulose, polyacrylic acid, maleine hydride copolymers or the like. The main disadvantages of such procedures are shown, for example. Because gelatin is a natural material, the properties of the feedstock can be very variable, except that further co-conservation can only be carried out at low concentrations of aqueous solutions, with long-term and technologically demanding processes and the walls of the microcapsules thus obtained. without further processing of very poor mechanical properties.

For inter-surface polymerization microencapsulation processes (e.g., EP 107,957; US 4,324,817; EP 16,378; DE 3,421,865; GB 1,581,255; US 4,228,216; DE 3,635,821; US 3,429,827; US 4,000,087 and U.S. Pat. No. 4,758,048), wall-forming reactants are located in both the oil (hydrophobic) and aqueous (hydrophilic) phases. The wall or. the envelope of the microcapsule is formed at the boundary between the oil / water phases; therefore, the wall thickness in all microcapsules is proportional to the size of the microcapsules, whereas in the case of microcapsules obtained e.g. by coacervation process or in situ polycondensation process of all microcapsules of equal thickness. This circumstance undoubtedly expresses a certain advantage, but unfortunately it is difficult to prepare microcapsules whose walls would at the same time have satisfactory mechanical properties. With the formation of the wall (for which, for example, polyol / isocyanate, polyamine / isocyanate and polyhydroxy compound / epoxy compound are suitable as reaction pairs), the wall also complicates the contact between the reactants, so that the further course of the reaction depends essentially on the possibility of diffusion through the wall already created. The aforementioned disadvantages result from such processes, which are manifested in particular in the reactivity of the reactants, the incompleteness of the reactions and, last but not least, in the possibility of reacting with one of the components of the nucleus, which of course makes it impossible to microcapsule many of these substances.

For in situ microencapsulation processes (in particular in situ polymerization or polycondensation of amino-formaldehyde resins, e.g. US 400.140; US 4.1000.103; CA 1.108.944; US 4.675.249; EP 826635; EP 133.295; EP 237.054; DE 3.626. 187; DE 3.532.878; JP 137.852; DE 3.709.586; YU 18623-P-l319 / 84) all available wall material comes only from the aqueous (continuous) phase. In an idealized process, all the wall material would be known in a known way, e.g. by changing the pH or temperature, it can be eliminated or eliminated. isobaric, evenly distributed over the entire available surface of the microcapsules, therefore the wall thickness of all microcapsules - regardless of their size - is the same. Aminoformaldehyde resins (melamine-formaldehyde and urea-formaldehyde or mixtures thereof) were mainly used as wall materials, in particular some of the older processes (eg GB 1.301.052 or GB 1.156.725), but also some of the more modern ones (eg DE No. 3,709,586 or U.S. Pat. No. 4,333,849), which is difficult to control, so they have been replaced, especially during the envelope formation or hardening, by processes characterized by the presence of anionic polyelectrolytes (modifiers), which primarily serve as an emulsifier, further triggering the polycondensation of the amine component. and aldehyde components or amino-formaldehyde precondensate in a specific way (so that polymerization occurs only on the surface of the emulsified oil droplets and not throughout the aqueous phase), and even after the polymerization is completed, they also assume the role of a carrier binder. This results in simpler operation of the process and also good mechanical properties of the microcapsules. ervation or e.g. with the interfacial polymerization process, the in situ polymerization process is technologically much easier to conduct, and thus microcapsules with better mechanical properties can be obtained, while the microcapsules emulsion has a high dry matter content at low viscosity.

Microencapsulation of fragrances, in particular e.g. of the essential oils; by the in situ microencapsulation method as described in YU 18623 (P1319 / 84). The process was cited in such a way that in an aqueous solution of the modifier (e.g., polyacrylic acid, ethylene and malic anhydride copolymer or styrene and maleic anhydride copolymer and mixtures thereof), in an amount of from 1 to 15% by weight of the modifier emulsify an oil funnel with an additive content (an compound or mixture of compounds where one or more functional groups such as -OH, NH2, NH-R, COOH, CONH2, CONHR are attached to the oil dye , where R stands for C1-C4 alkyl radical), in an amount of from 0.1 to 30% by weight of the additive based on the weight of the oil dye, and added aminoformaldehyde precondensate, such as di- to hexamethiol melamine or di- to tetra metiol urea, methylated methylol melamine or methylated methylol urea and low polycondensation products thereof (wherein the methylation rate of methylated methylol melamine or methylated methylol urea is 0 100%, the ratio of modifier to amino formaldehyde m precondensate from 10: 1 to 1: 1), which polymerizes at elevated temperature (50-100 ° C) and at a pH of 4 - 7 and surrounds the emulsion of the oil dye.

v

If the micro-encapsulation of fragrances according to the above procedure is used as a core material instead of a funnel of dyes, e.g. Essential oil, unfortunately, the use of such a process in the microencapsulation of fragrances is inevitably linked to some disadvantages, which are manifested in particular in the fact that the distribution (by size) of the emulsion particles and the coated oil particles - microcapsules is different, which is related in particular to irregularities during the curing phase. oz. rock formation. A further disadvantage is the poor physical properties (especially mechanical resistance) of the microcapsules thus obtained. In addition, the viscosity of the emulsion of the microcapsules in this case is higher than in the case when the micro-encapsulation of the funnel dye, the formation of unfavorable agglomerates or. clusters of microcapsules, which are particularly undesirable for coating paper or other similar carrier, so that most fragrances cannot be microcapsulated or applied at all in practice by this process. apply them in microcapsules to a carrier that would be practically usable.

In general, water-soluble fragrance components (with functional groups -OH, -NH, -C = O, -CHO or eg COOH) interfere with the microcapsulation process in the smallest amounts. On the one hand, when emulsifying, they can pass into the aqueous phase, resulting in the local formation of the modifier and, consequently, changing the particle size due to the decrease in the emulsifying ability, which is further enhanced when heated to the polymerization temperature because the solubility of the acids at an elevated temperature is even higher, which makes the polymerization resin deposition on the surface of the oil particles even more difficult. On the other hand, there is an uncontrolled polymerization of the amino-aldehyde resin by weight or by weight. to the reaction with the amino-formaldehyde resin, which changes the physical (especially mechanical) properties of the wall.

One way to solve the problem previously discussed is by removing the free acids and the water-soluble component from the fragrance composition before the emulsification phase, which is feasible by repeated extraction with water, resulting in the distribution of free acids and water-soluble components between hydrophobic and hydrophilic phase (in accordance with Henry's distribution law), as described in Yugoslav patent P-1319/84, from which, respectively. the superstructure of which is the process of the invention.

According to the invention, the method of preparation of carriers impregnated or coated with micro-encapsulated fragrances is designed so that, in the preparation of the microcapsules emulsion, the water for extraction of water-soluble components is emulsified into a solution of essential oils and separated from the oil after extraction of the core material. Essential oils or intended fragrances, in particular natural essential oils, synthetic fragrances or a mixture thereof, are provided, either as pure fragrances or diluted with suitable diluents such as phthalates, myristinates, adipates, higher non-aromatic hydrocarbons, microencapsulated or. microencapsulated. It is particularly important to extract water-soluble components from the solution of essential oils in thinners. Upon wall initiation, the temperature gradually rises from a value corresponding to about 50% of the volatility temperature of the respective essential oil, respectively. fragrances, up to a temperature corresponding to approximately 90% of the volatility temperature of each essential oil, respectively. fragrances. In the preparation of the coating or. Depending on the carrier, the micro-encapsulated fragrance, binders, organic and / or inorganic pigments and fillers, antifoams and viscosity regulators are added to the impregnation preparation. In the coating of the carrier, the suspension coating is applied by means of a scraper, an air knife, cylinders, and in the impregnation, the carrier is guided through an impregnation tub with an impregnating preparation as a woven or non-woven textile, paper or plastic film.

Possibilities of micro-encapsulation of fragrances based on modified or. of the advanced process of the invention, comparatively with respect to known methods (in particular, according to Yugoslav Patent P-1319/84) are shown on the basis of the examples described in more detail below.

The resulting particle size distributions after emulsification and curing are shown in FIG. 1-6. The size of the microcapsules was measured with a Coulter-Counter TA Π apparatus after the emulsification phase and after the curing phase. Before and after curing, the emulsion was examined with an optical microscope to record the presence of any agglomerates of the microcapsules. The hardness of the microcapsules was assessed by auxiliary microencapsulation, with 3% funnel crystalline lactone (abbreviated CVL) added to the core of the microcapsules containing the fragrance, and the microcapsulation performed according to the same procedure as in the fragrance itself. The hardness and consequently the diffusivity and mechanical properties of the microcapsules can be assessed by means of a hardening test (according to method 1, which will be described below) and an erasure test (following method 2 described below). Microcapsules emulsion containing microcapsulated funnel dye in addition to fragrances can be used to regulate the viscosity (at 100 to 150 mPas) by dilution with water, and it can be coated with paper (50 g / m ² ), for example. using a wire scraper. The application can be dried (for example with a conventional hair dryer) to a value of about 5 g / m ² to give a so-called CB sheet.

When performing the hardening test according to the aforementioned method 1, the CB sheet or the coatings are coated. its coated side with silicic acid salt (Kisselsol 300 F, Bayer) and dried by e.g. using a regular hair dryer. Upon drying, the acid crystallizes and damages the wall of the microcapsules. However, since acid is also the developer of funnel dye, it also reacts with the dye funnel and thus stains and the latter can be measured with a densitomer (optical density meter). For comparison of two types of microcapsules it is sometimes sufficient to compare the coloration with the naked eye. Strength or. the intensity of staining is inversely proportional to the strength of the wall of the microcapsules, and it is also known from experience that they have microcapsules that are stronger or stronger. the more intense the color, the greater the diffusivity.

When performing the erasure test according to the aforementioned method 2, it is possible to determine the mechanical resistance of the microcapsules, especially against the shear loads, which play an important role in manipulating the coated supports. A CB sheet with microcapsules (eg A4 format) is placed on a smooth plate, e.g. to the table, with the coated side facing up. A CF sheet (i.e., a dye developer sheet) is placed on the CB sheet so that the coated sides of the two sheets are in contact with each other. The CF sheet is then weighed with a weight of 0.5 kg, with a diameter of 45 mm, and then the CF sheet with the weight is dragged over the 200 mm CB sheet. The mechanical resistance of the wall of the microcapsules can be evaluated comparatively. to be determined on the basis of the intensity of staining of the CF sheet. Strength or. the mechanical resistance of the wall is inversely proportional to the intensity of staining.

In the first embodiment of the process according to the invention, micro-encapsulated peppermint oil was used. 50 g of essential oil (peppermint) were dissolved in 150 g of i-propyl myristate. Subsequently, 20 g (possibly 15-25 g) of deionized water were emulsified in this mixture using a dissolver mixer at 800-2000 min. After stirring for 15 minutes, the resulting emulsion was poured into a separating funnel and the emulsion was allowed to burst, after which a layer of water was decided. The oil thus obtained was re-emulsified using a dissolver mixer at 800 - 2000 min -1 in 300 g of a 5% solution of styrene-maleinanhydride and 80 g of methylated melaminformaldehyde precondensate with a pH between 4.5 and 5.5 (preferably 5.5), and a viscosity of between 100 and 500 mPas (preferably 200 mPas). The emulsification was carried out at room temperature for about 15 min, but generally lasted until the desired particle size was obtained, between 3 and 10 pm. Then we mix or mix. the emulsion was heated to 60 75 ° C (preferably 70 ° C) and this temperature was maintained for 1 to 2 hours while stirring. Then the microcapsules were closed and the emulsion cooled and the curing reaction was stopped by the addition of 5 g of 20% NaOH. The reaction formed formaldehyde was removed by the addition of 10 g of 20% sodium bisulfite.

The first comparative example was the procedure according to the aforementioned Yugoslav patent P-1319/84, without changes, but instead of the funnel dyes, we microcapsulated peppermint essential oil. In contrast to the previously described, the water treatment phase was omitted in this process. The microcapsules thus obtained had a significantly poorer particle size distribution and poorer mechanical properties than those obtained by the process of the invention.

In another embodiment of the process of the invention, a mixture of lemon essential oils (citron) and mint (peppermint) was used instead of peppermint essential oil. The process characteristics and quantities corresponded to those stated in connection with the first embodiment of the process according to the invention.

In the third embodiment of the process of the invention, a mixture of eucalyptus and peppermint essential oils was used instead of peppermint essential oil. The process characteristics and quantities corresponded to those stated in connection with the first embodiment of the process according to the invention.

In the second and third comparative examples 2 and 3, the procedure was the same as in the first comparative case, except that a mixture of lemon essential oil (citron) and mint (peppermint) was used in the second comparative case, in the third comparative case, in the third a mixture of eucalyptus and peppermint essential oils.

In addition, microcapsules were prepared which, in addition to the aforementioned fragrances, also contained a crystalline lactone 3% funnel dye.

The resulting particle size distributions after emulsification and after curing are shown in FIG. 1-6, while the mechanical properties of the microcapsules measured according to the previously described method 1 or 1. Method 2 (Microcapsules with 3% funnel of dye Crystalline lactone) shown in Table 1 below.

In FIG. 1 shows the particle size distribution as a result of the first embodiment of the process according to the invention, using peppermint essential oil as a fragrance.

For comparison, in FIG. 2, a particle size distribution was shown as a result of a method known to date (P1319 / 84), with peppermint essential oil being used as a fragrance in this case as well.

In FIG. 3 shows a particle size distribution as a result of another embodiment of the process according to the invention, using a mixture of peppermint and lemon essential oils in this case.

For comparison, in FIG. 4, a particle size distribution is shown as a result of the use of the method known so far (P1319 / 84), and in this case a mixture of essential oils was also used as in the previous case - in connection with FIG. 3 to the said procedure.

In FIG. 5 shows a particle size distribution as a result of a third embodiment of the process according to the invention, using a mixture of eucalyptus and peppermint essential oils in this case.

For comparison, in FIG. 6, a particle size distribution is shown as a result of the application of the method known so far (P1319 / 84), and in this case a mixture of essential oils was also used as in the previous case - in connection with FIG. 5 to the said procedure.

From the attached Figs. 1 - 6, the resulting particle size distributions after emulsification and after curing are shown, while the mechanical properties of the microcapsules measured according to the previously described method 1 and 6, respectively. Method 2 (Microcapsules with 3% funnel of dye Crystalline lactone) shown in Table 1 below.

Example Hardness test Erasure test Example 1 good consolation weak swab Prime example 1 Medium good fatigue a strong swab Example 2 good fortitude weak swab Prime example 2 poor fortification very strong swab Example 3 good consolation weak swab Prime Example 3 poor fatigue very strong swab

Table 1

In this way, it is possible to obtain carriers, both impregnated and solely coated with microcapsulated fragrances, which prevent the evaporation of the fragrance and eliminate the influence of the environment on the fragrance, or by means of the preparation of carriers impregnated or coated with microencapsulated fragrances. sensitive components thereof. Therefore, the fragrance carriers thus obtained do not require the use of environmentally friendly, impermeable packaging. Because the fragrance begins to release in a convenient way, when, for example, during use, the walls of the microcapsules are damaged by pressure, instead of the involuntary permanent and therefore short-term effect of the fragrances, the desired and long-lasting effect of the fragrances is enabled. In this way, the usefulness of the carriers thus obtained is extended, inter alia because the wall of the microcapsule protects the fragrance from diffusion, whereby in practice only slight amounts of fragrance are released by diffusion. Last but not least, the carriers thus obtained can be further processed in a properly selected manner, e.g. to print on a printing machine without causing loss of fragrance.

Claims (3)

PATENT APPLICATIONS 1. A method of preparing carriers impregnated or coated with microencapsulated fragrances, comprising preparing the emulsion of the microcapsules, preparing the coating and coating or impregnating the carrier, the preparation of the emulsion of the microcapsules also comprising, after emulsion preparation, emulsifying the core material into a solution of the design of the wall, the initiation of wall formation by raising the temperature and / or changing the pH value, and in addition ending or. discontinuation of the microcapsulation by changing the pH value and thus by stopping the polymerization, characterized in that, in the preparation of the microcapsules emulsion, the water for the extraction of water-soluble components is emulsified into the solution of essential oils and separated from the oil after extraction of the core material. envisaged essential oils or intended fragrances, in particular natural essential oils, synthetic fragrances or mixtures thereof, whether as pure fragrances or diluted with suitable diluents such as phthalates, myristinates, adipates, higher non-aromatic hydrocarbons, microencapsulated or. micro-encapsulated, and wherein water-soluble components are extracted from the solution of the essential oils in the diluents by means of water, except that at wall initiation the temperature is gradually increased from a value corresponding to about 50% of the volatility temperature of the respective essential oil, respectively. fragrances, up to a temperature corresponding to approximately 90% of the volatility temperature of each essential oil, respectively. fragrances, except that in the preparation of the coating or. Depending on the carrier, the impregnation preparation adds microencapsulated fragrance, binders, organic and / or inorganic pigments and fillers, antifoams and viscosity regulators. In addition, when coating the carrier, the slurry coating is applied by means of a scraper, air knife or cylinders. when, during impregnation, the carrier is guided as a woven or non-woven textile, paper, cardboard or plastic film through an impregnation tub with an impregnation preparation. Method according to claim 1, characterized in that in the preparation of the microcapsules emulsion, during the preparation phase of the core material, the water for extraction of water-soluble components is emulsified into a solution of essential oils and after extraction is separated from the oil by gravity in separating vessels. Method according to claim 1, characterized in that in the preparation of the microcapsules emulsion, during the preparation phase of the core material, the water for extraction of water-soluble components is emulsified into a solution of essential oils and after extraction is separated from the oil by centrifuge.